Mercury-vapor rectifier



Dec. 413, 1927.

L. WIMBERGER MERCURY VAPOR RECTIFIER Filed June 1926 Patented Dec. 13,1927.

UNITED STATES LEOPOLD wmnnnenn, or VIEN A, Austrian.

MERCURY-VAPOR RECTIFIERv Application filed June 30, 1926, Serial No.119,683, and in Austria August 26, 1925.

My invention relates to mercury vapor rectifiers for convertingalternating current into direct current. In such rectifiers a specialstarting device forstriking the arc is necessary. It has been alreadyproposed to use for this purpose a heating filament which, when heated,causes vapor of mercury to be evolved whereby the are is struck and therectifier is started without tilting the rectifier bodily and withoutthe use of a movable auxiliary electrode.

In the rectifiers proposed the heating filament, however, dipped freelyinto the mercury and therefore was liable to move irregularly, forinstance in the case of portable rectifiers or rectifiers used onvehicles whereby the reliability of the rectifier is greatly impaired.

One of the objects of my invention is to avoid this inconvenience and toprovide a compact reliable rectifier of the class above referred to.

Up to now for the manufacture of glass rectifier vessels or bulbsspecial sorts of glass had to be used which were not only expensive butalso required particular care and skill in blowing.

It is one of the objects of my invention to provide means wherebycheaper sorts of glass, much easier to blow may be utilized in themanufacture of the glass bulbs of rectifiers.

With these objects in view my invention firstly consists in that bothends of the heating filament are secured to supply wires, the filamentor one ofthe supply wires passing through the mercury and conducting thealternating current to be rectified to the mercury cathode. Furthermoremy invention consists in an improved construction of the anode wherebythe reliability of the rectifier in operation is greatly increased. The

- anode is constructed according to my invention as a metal cylinderlocated above the surface of the mercury; this anode therefore acts soto speak as a chimney in which con tinuously rise the mercury Vaporsevolved, these vapors being subsequently condensed on the walls of thebulb.

Finally my invention consists in that I add to the mercury a smallproportion of thorium oxide.

In the annexed drawing I have illustrated by way of example a rectifierconstructed in accordance with the present invention.

4 caused to Fig. 1 is a circuit fier,

Fig. 2 is a sectional elevation ofthe rectifier used for charging thesecondary battery. v

Through the primary winding of a transformer 1 alternating current 1s.caused to flow. The mercury cathode 2 of the rectifier 3 is connected bya wire-4 to the terminal 5 of the secondary winding of thetransformer 1. The anode 6 is connected to the terminal 7 by a line 15which includes an ammeter 8, the battery 9 to be charged and anadjustable resistance 10. A heating filament 11 serves for heating themercury, part of such filament dipping into the mercury. Currentis-sup'plied to the heating filament by the wires 4 and 12 and a switch13 from taps ofv the transformer. The anode consists of a metalcylinder, preferably of iron, located vertically above the mercurysurface and diagram of the rectifunncl shaped at its bottom end.

For starting the rectifier the switch 13 is closed. A current flowsthrough the heating filament 11 heating the latter and thereby also themercury so that mercury vapors are evolved. When the latter come intocontact with the anode 6 connected to the other terminal of thesecondary the arc is struck whereby the rectifier is started. The switch13 is then opened which might be brought about automatically by anelectromagnet not shown which is energized by the current flowing in theline 15.

The mercury vapors rise in the metal cylinder and are condensed on thecool walls of the bulb 16. and return in the form of drops into thecathode.

Fig. 2 is a sectional elevation of the rectifier, the wire 4 passesthrough a quartz tube 18. The second supply wire to the heating filamentpasses through the cylinder 14 enclosing a quartz tube 19 which endsslightly above the bottom end of the cylinder. The anode is held inposition by a support 20 serving at the same time as a supply wire forthe same and also holds in position the wire 4;.

In case the rectifier is designed for higher loads the switch 13 is notopened after the rectifier has been started, but current is permanentlyflow through the heating filament in order to avoid any dangerouscooling of the mercury, in case of large changes of the currentintensity.

A particular advantage of the rectifiers constructed according to thepresent invention consists in that they may be manufactured similarly asordinary incandescent lamps and therefore may be readily mounted inposition and exchanged if necessary.

I have discovered that a rectifier operates under much more favorableconditions if mercury is used which contains an addition of thoriumoxide. The proportion of thorium oxide is about three parts by weight ofthorium oxide to one hundred thousand parts by weight of mercury. Bythis addition the are becomes much more steady and Q has a notably lowertemperature; the pressure of the mercury vapor is lower and neverthelessits conductivity in one direction is greater. This permits as abovestated to use for the manufacture of the glass vessels or bulbs of therectifiers sorts of glass which are less expensive and more readilyblown than'the sorts of glass which it was necessary to use heretoforefor such bulbs.

While in the usual rectifiers a high vacuum i had to be maintained, inthe resent rectifier a much lower vacuum will e found sulficient. Owingto the steadiness of the arc,

throttle coils and equalizing coils may be dispensed with. The bestresult-s are obtained by using mercury with an addition of thorium oxidein the rectifier hereinbefore described in which for starting therectifier a heating filament is used. By using mercury with an additionof thorium oxide the costs of manufacture of the above rectifier may begreatly reduced.

hat I claim is:

1. In a rectifier'the combination of a bulb, a rigid metal anode, amercury. cathode, a heating filament, a supply wire for each of the endsof the heating filament, both supply wires being sealed into the part ofthe bulb opposite to the mercury cathode, the supply wires passingdownwards through the bulb and at least one of them dipping into themercury.

2. In a rectifier the combination of a bulb, a rigid metal anodecomprising a vertical hollow cylinder open at both ends, a mercurycathode, the said anode being arranged vertically above the surface ofthe said mercury cathode, a heating filament, a supply wire for each ofthe ends of the said heating filament, at least part of one of the saidsupply wires and a piece of the filament connected thereto passingthrough the said mercury cathode.

3. In a rectifier the combination of a bulb, a rigid metal anode,comprising a vertical hollow cylinder open at both ends having itsbottom end conieally enlarged, a mercury cathode, the said anode beingarranged vertically above the surface of the said mercury cathode, aheating filament, a supply wire for each of the endsof the said heatingfilament, at least part of one of the said supply wires and a pieceof-the filament connected thereto passing through the said mercurycathode.

4. In a rectifier the combination of a bulb,

a rigid metal anode, comprising a vertical hollow cylinder open at bothends having its bottom end conically enlarged, a mercury cathode, thesaid anode being arranged vertically above the surface of the saidmercury cathode, a heating filament, a supply wire 5. In a rectifier thecombination of a bulb,

a rigid metal anode, comprising a vertical hollow cylinder open at bothends having its bottom end conically enlarged, a mercury cathode, thesaid anode being arranged vertically above the surface of the saidmercury cathode, a heating filament, a supply wire for each of the endsof the said heating filament, at least part of one of the said supplywires and a piece of the filament connected thereto passing through thesaid mercury cathode, the heating filament pass ing axially through thesaid vertical hollow cylinder, and a quartztube being provided withinsuch cylinder, the bottom end of the said quartz tube being above thebottom end of the said cylinder, a conductive support for the saidvertical cylinder directly connected to one of the said supply wires,such support comprising an insulating holder located outside the saidvertical tube and adapted to support the other supply wire.

6. In a rectifier the combination of a rigid metal anode and a cathodeconsisting of mercury with a small quantity of thorium oxide suspendedin such mercury.

7. In a rectifier the combination of a rigid metal anode and a cathodeconsisting of mercury with an addition of about three hundred thousandthparts of thorium oxide.

LEOPOLD WIMBERGER.

